Telephone system



March 17, 1942. R..HOEFERT ET AL TELEPHONE SYSTEM 5 Sheets-Sheet 2 Filed June 13, 1940 `/-vN-roe REmHoLD uoEFERT and Konsrnurm sermone-R HToE/#EY March'17, 1942-s R. HOEFERT ET Al.

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R. HOEFERT ET AL TELEPHONE SYSTEM Filed June 13, 1940 5 Sheets-Sheet 4 March 17, 1942. R. HOEFERT ETAL TELEPHONE SYSTEM 5 Sheets-SheerI 5 Filed June 13, 1940 Patented Mar. 17, 1942 UNETED STATE PATENT OFFICE TELEPHONE SYSTEIVI Reinhold Hoefert, Berlin-Gatow, and Konstantin Schrder, Berlin-Staaken, Germany, assignors to Fides Gesellschaft fr die Verwaltung und Verwertung von gewerblichen Schutzrechten mit beschrnkter Haftung, Berlin, Germany, a

corporation of Germany Application June 13, 1940, Serial No. 340,294

In Germany May 16, 1939 (ci. 17e-1s) 4 claims.

The present invention relates to improvements in telephone systems and more particularly to a circuit arrangement for multi-exchange telephone systems the exchanges of which are interconnected in dilerent ways. Thus a call can be set up over the various junction lines provided or over dilerent exchange stations. The latter is, for example, the case if as Well as junction lines between the toll exchanges or between the rural main exchanges and the associated toll exchanges so-called tie lines are provided between rural main exchanges and other exchanges of the same or of another toll area over which traffic may be developed. The required exchange station can then be reached from the rural main exchange for example over the junction lines leading to the toll exchange erover tie lines. n

In order to maintain the junction lines to the toll area exchange free, especially if traine to distant exchanges is concerned, in the event of connections which may be made over tie lines precautions are taken that the seizing of a highvalued junction line is only possible if no tie line is available for building up the required connection. For this purpose code repeaters are provided at the connectingmeans available to the calling subscriber which receive the numerical impulse series transmitted for marking the required direction and determine according to the said signals whether tie lines 'are available in the required direction in order that, if necessary, a free line of this kind should be switched to the connecting devi-ce seized by the calling subscriber. According to Whether this line leads directly to the required exchange station or at rst to another exchange station over Which the required connection can then be set up, a certain number of the stored numerical impulse series are sent out from the code repeater. I1" it is desired to prevent the code repeater being taken into use when connections are set up within the rural main exchange connecting means must be provided the seizing of which is only undertaken after the selection of one or more numerical impulse series by the calling subscriber so that the code repeater must determine the numerical impulse series sent out before its seizure in order to determine the path to be used and, if necessary, to be able to transmit the impulses peater is not at the sole disposal of any one connecting device in the exchange in question but .is provided in common for several connecting devices, it must determine by which of these connecting devices it has been seized in order that the selected free line should be connected With that connecting device seized by the corresponding calling subscriber.

To this end it has been proposed to mark the toll exchange or partof the toll exchange marked by the calling subscribers initial numerical selection in the code vrepeater by means of a relay and to determine the connecting .means used thereby by by-path testing in dependence on the according to the path which is chosen for the This is attained` therein that a step-by-stepv switch mechanism closes the test circuits for the individual code repeaters one after the other so that at one time one testing operation only can' take place. This switch mechanism can, hoW- ever, only operate with a, limited speed since the selector of the code repeater determining the seized connecting device must traverse a large number of contacts during each operation of the switch device.

According to the following invention the determination of the toll area selected by the calling subscriber and the connecting means seized for this purpose is simplified and false operation is prevented. rThis is attained therein that switch devices are associated with the code repeaters, to the contacts of Which are connected the connecting devices used by the code repeater in groups according to their traino directions and also singly so that by the setting of the switch device simultaneously the signal selection and setting up of the connecting path to be reproduced by the code repeater according to the direction of the seized connecting device is determined-and the connecting device connected With the selected connecting path is also determined.

An embodiment of the invention is Aillustrated in Figs. 1-5. Fig. l isa schematic networky layout of a multi-exchange area With a number of connecting paths, While in Figs. 2 and 3 a section of the rural main exchange (NHA'IZ) is shown attainable by a calling subscriber over a connecting means Uel2 to-which a code repeater (e. g. KZ!) common to several connecting devices may be connected over a connectionselector (for example AW2). The selectors (Ws, Wa, Wb, Wc) are shown for connecting the connecting lines (S, A, B, C) to the connecting means. In Figs. 4 and 5 a code repeater (e. g. KZI) is shown with the selectors necessary for its diierent functions and the signal control relay. Battery and earth are omitted where they are not necessary in order that the invention ybe explained to simplyfy the drawings. The setting magnets for the selector with the associated revertive relay are not shown in order to explain more simply the operation in question. The contact banks of each signal selector are shown schematically in order to keep the circumference of the selector within a reasonable space; and a limited number of wipers are shown in the given embodiment. For the selectors in Figs. 4 and 5 with the reference d step-by-step selectors are used and for those with the reference m motor selectors are used; naturally other types of selectors may be used.

`.In Fig. 1, two toll area exchanges are shown, BAI ,and BAT, to which rural main exchanges, for example NHA12,13, 'M or NIIA|2, I3, |`4 are connected. To some of the rural main exchanges are 'connected junction centres, for example KA`|2|, 121|, or Iii-U33, |34, |35 from which iinal exchanges, e, g. EA'Z24I, 72132, 'l2-'i3 or EAI35I, |352 branch off.

The connecting means Ue|2 shown in Figs. 2 and 3 with the associated selectors Ws, Wa, Wb, Wc, is like the code repeater KZI shown in Figs. 4 and 5, provided in the following example in the rural main exchange NHA'IZ. From this exchange are connected so-called S-lines to the associated toll area exchange BA1, which is connected over junction lines with the toll area exchange BAL Also between the rural main exchange NHAIZ and the toll area exchange BA| A-lines are connected, between the rural main exchanges NI-IA12 and NIIA|3 B-lines, and between the rural exchange NHA'IZ and the juno tion centres KAI33, |34, C-lines. Between the other exchanges likewise different junction lines can be connected in any preferred manner.

The S-lines are lines which end at an S-group selector for .selecting a toll exchange. The A-lnes end in an A-group selector which provides for the selection of a rural main exchange. The B-lines lead to a Bgroup selector which provides for the selection of a junction centre while the C-lines lead to a C-group selector and are provided for the selection of a final exchange.A

From the network layout shown in Fig. 1 it will be seen that a calling subscriber belonging to the rural main exchange NHA'IZ may reach, for example, the junction centre KA|35 over the S-line to the toll area exchange BA1 and then over BAI-NI-IAIS, or over A-line to the toll area exchange BA| and `then over NIIA|3 or over Bline to the rural main exchange NHAI3, or directly over the Celine. The marking number for access to this junction centre is 135 and the rst gure l serves for setting a group selector GW in the rural main exchange NHA'lZ on the rst decade, in which a free connecting means is hunted e. g. the connecting means Ue|2 connected to the contact 2. To this connecting device (of Figs. 2 or 3) a free code repeater e. g.

KZI is connected over a hunting switch AWZ.

This code repeater which is shown in detail in Figs. 4 and 5 repeats the marking number already received from the group selector GW (the number 1) by setting the wipers dIIJ--dlS according to setting of the wipers mIU-ml'|; it receives the further impulses transmitted from the ca1ling subscriber consisting of three and five impulses by setting the wipers (12B-(122 and d3-d3l; if necessary then a further impulse series is received by setting the wiper d dl. By a corresponding setting of the m20-m26, m3|-m36, m40-m46, m50-m56, and 1160-1162. the junction line available in the required direction is determined, the chosen line is connected with the connecting means Ue|2 seized by the calling subscriber and, according to the line connected, determines how many impulse series are to be sent out from the code repeater KZI, determined by the setting of the wiper d50, for reaching the required junction centre KA|35.

The switch operations described above take place in detail in the following manner:

After the group selector GW in the rural main exchange NHA'I2 (Figs. 2 and 3) is set by the numeral 1 on the decade l, it hunts for a free connecting means. If, for example, a connecting means Ue|2 connected to the contact 2 is reached a circuit for the relay C is completed over the test conductor over the corresponding c-wiper which by connecting its high resistance winding II over the contact c holds the connecting means locked against further seizing by another group selector. The connecting selector AW2 associated with the connecting means Ue|2 is prepared to be connected With a free code repeater e. g. KZI and the relay T of the hunting switch AW2 is energised over: earth, battery, WzS (Fig.

4), contact |3cl, conductor I, wiper a2 of the lla, 6c, earth. The relay P, when its high re sistance winding I is short-circuited over contact lp, locks the code repeater KZI against seizing by another hunting switch. By closing the Contact 8p the impulsing relay Al of the code repeater KZI is connected over: Wiper c2 of the hunting switch AW2, conductor 3, relay Al, contact MCI, Wi, battery, earth. By the closing of the contact 9p the circuit over which the code repeater KZ! transmits numerical impulses is prepared over the wiper d2 of the hunting switch AWZ and the conductor 4.

In the code repeater KZI after relay Cl is energised the associated contacts are operated so that relay C2 is energised, contact 2|c| closed and relay CI is held energised over its series Winding III. Further, after the code repeater KZI is seized, the selector provided with Wipers mill-mV! is set in motion, in a manner not of interest in this invention, in order to determine the seized connecting means Uel2. The selector is in motion until its wiper ml reaches the conductor connected to the contact 2. Then the relay Pl is energised over: (Fig. 2), earth, battery, WzS, contacts 151', |2p, wiper f2, conductor |2 (Fig. 5), wiper ml on contact 2, relay Pl, contacts 2|q|, 22cl, earth. The relay PI is thus energised when the selector is stepped-on to the second contact; in a manner not shown here, further stepping by the selector is prevented. Wiper mll set with the wiper mIU marks, in the contact bank which it traverses, the connecting means Ue|2 by being set on the second contact. In this contact bank, however, contacts are multipled according to the number of connecting means required in the corresponding direction. To simplify matters two connecting means are providedin the direction I in the present ernbodiment.

After the relay PI is energised, the relay QI is energised over the contact 2311i and holds itself energised in a holding circuit over its contact Zlql. Moreover, depending on the control relay, not shown, the selectors with the wipers mG-m and mtgm56 are set in motion until the wipers mail and m50 reach the contacts marked by the wiper ml I. When the wipers m40 and m50 are resting on the contacts I, the relays P2 and P3 are energised over: relay P2, wiper m40 on contact I or relay P3, wiper m50 on contact I, wiper 'm'I I on contact 2, contact 2502.

Apart from the setting of these selectors, after relay QI is energised, in a manner not shown here, the selector with the wipers dill to 155, is

stepped-on until the relay Pfl is energised over I the wiper dll? and the contact marked by the wiper ml I. This also takes place when the switch has taken one step. The next numeral is thus determined. The multipling between the steps of the wipers dit] and mII is-so selected that the number to be transmitted is the rst place of the marking number and is also the number of steps which the selector with the wipers cZIIl-dl is distant from its zero position. rhe rst impulse series is subsequently routed over the wiper dlr: set cn the contact i, and is transmitted by the selector with the wiper (15d.

After relay Pd is energised, the relay Q2 is energised over the contact p, The impulsing relay AI of the code repeater KZI receives the e further impulse series transmitted from the calling subscriber over the conductor 3. By the next impulse series the selector with the wipers 2li-0123 is set and, since the next impulse series consists of three impulses, reaches the contact 3. Hereupon, in a manner which is not shown, switching over takes place so that the third impulse series (5) is transmitted from the relay AI to the selector with the wipers (E38 and dl. If necessary a 4th impulse series is subsequently transmitted to the selector of the wiper ddl).

In the present case all three possible tie lines (A, B, C) are determined by the first three irnpulse series. v

The relay Q2 energised over the contact 25nd after relay P4 is energised during the determination of the iirst numeral (l) connects the selectors in a manner which is not shown, with the wipers 1MB-m26 and Z39- m33 in an automatic stepping circuit. They are stepped-on until the wipers m2o and m38 reach that contact which is marked by the wiper dI I set on the contact I. The test relays P8 and P9 of these two selectors are now -energised and stop the selector. The energising circuit is completed over; relay P8, wiper m28 or relay PS, wiper m3@ on contacts II, multipling wiper dl I on contact I, contacts 35u2, 36u3, and MC2. After contacts Sp and 38229 are closed, relay U3 is energised over: contacts 31o/5, 38179, 39138, llllq2. Relay U3 breaks the circuit for the relays P8 and P9 at 3Su3 so that the two selectors are again switched in.

In the meantime, by the closing of contact 43o/5 a new test circuit is prepared over the wiper dil, for, after the second impulse series from the calling subscriber setting this wiper the relay Q5 is energised over wiper (123.

Since in the above case this impulse series consists of three impulses the wiper d2!! is set on the contact 3, the two selectors with the wipers mim-m26 and m30-m36 are in motion until the wipers m20 and m3@ reach the contact I 3. The relays P8 and P9 are energised over: wiper m29 or m39 on contact I3, multipling, wiper d`2ll on Contact 3, contacts d2u2, 43415, and No2. The relay QQ is energised over the contacts M115, 435119,46@ and 47:12 and is held energised over its contact Tlqd. II"he relay Q5 is rcstored by the short-circuit over the contact fi-8c4. A further setting operation of the two selectors is prevented.

In the Contact banks of the selectors which are swept over by the wipers m2I-m26 and m3I-m35 are contained all the possible connections in the main and tie directions. The contacts which may be reached by these wipers are multipled in a denite manner with the contacts attainable by the wipers mill-m46. According to theabove description, for example, vthe wipers m40-m46 corresponding to the groups of the seized connecting means Uell are set on the contact I while the wipers 12d-m26 and m3@- m36 are stepped corresponding to the first two impulse series (l and 3) and are set on the contact I 3.

In the circuit given in Figure 3 it is assumed that for the direction characterised by the three impulse series (I, 3, 5) the following possible connections may obtain:

IC-direction according to the numerical selection B-direction according to the numerical selection 13 A-direction according to the numerical selection l S- direction according to the numerical selection l The corresponding contacts I3 are therefore connected with the contact I of the contact bank traversed by the wipers mtl to mdc in the manner shown.

The multipling for the other directions is carried outy according to all the connections which are possible.

As shown in Figure l, three rural main exchanges NHAIZ, NHAES and NEL/lill may, for example, be connected to `the toll area exchange BAI. In this case then the contacts I2 to Id in the contact bank traversed by the wiper mZI are connected together and, since the toll area is associated with the group I, one step is taken by `the wipers mlll to m65 wired to the rst contact of the contact bank traversed by the wiper mill. If other A-lines are provided, in the contact bank traverse I2 to Ill should be connected and multipled with the rst contact of the contact bank'traversed by the wiper mil-2. This applies similarly for the B and C lines.

- As shown above the relay Qd is energised in the present circuit after the wipers m20 to m26 and mSI to m36 are set. The wipers d to -d2 are stepped-on in any known manner. As soon as contact 2 of the wiper dll is reached the relays PII) and PI I are energised in series over contacts 52c2, 88N, 5IqfI, relay PIIB, wiper d50 on contact 2, wiper m45 on contact I, wiper m32 on Contact I3 U35), wiper d3l on contact 5, contact SM2, relay PII. Over the contacts IrI,

53pm, the relay PI2 is connected to the wiper dSI. Since the wiper dl. is set at Contact 2 and the wiper m55 on the contact I (conductor oc) it can energise as long as a free C-line is available over the conductor vc. In this case the relay PI2 is energised over: contacts S'Irl, 53pm, relay PIZ, wiper cZGI on contact 2, wiper m55 on contact I, conductor vc, contacts 54120, 55mc,

by the wiper m22 the contacts Y relay Bc, battery, earth. In this circuit relay Bc is also energised and by closing its contact 565e the rotary magnet Dc of the selector Wc is connected over the contact 'Imc. This selector is in motion until the relay Mc is energised over earth, contacts 59120, 58bc, windings II and I of the relay Mc, wiper dc, conductor dc (Fig. 5), wiper mI6 on contact 2, wiper 1162 on contact 2, contact BpIZ. In this case the connecting device UeI2 seized by the group selector GW to which the free C-line is connected is connected over the selector Wc. The relay Mc by opening contact 5'Imc prevents further operation of the rotary magnet Dc. Relay NC is connected to the wiper c of the selector Wc over contact Slmc so that the relay is energised over: C-line, windings II and I of the relay Nc, contact BImc, wiper c of the selector Wc, relay R, contact 181', wiper e2 of the connecting selector AW2, conductor 5 (Fig. 4) winding I of the relay RI, contacts 'I9pI2, 800|, earth. In this circuit the relays R and RI are also energised. Conductor 5 is disconnected by the opening of the contact 18T. The holding circuit for the relays Nc and R is now extended over the contacts 13T, 'IIa and 5c, while relay RI (Fig. 4) is connected in a holding circuit over its winding II and the contact 82H. By the closing of the contact 641m the connecting device Ue|2 now connected to the selector Wc is locked, while by the closing of the contacts 62nc and 631m the speaking conductors are switched through. By closing the contact 65nc the relay Vc is energised so that the relay Mc is also held energised over its winding III and the contact 680e. When relay Vc is energised the seized C-line is disconnected from the conductor vc by the opening of the contact 54110 and this conductor is switched on to the next free C-line by the closing of the contact 100C. By the closing of the contacts 83T and 84? the conductors a2 and b2 in the connecting device UeI2 are switched through and by the closing of the contact 85H (Fig. 4) impulse transmission is started as will be explained later.

If a free C-line in the marked direction (135) is not available the relay PI2 cannot be energised over a corresponding inc-conductor; the wipers dII) to e162 are stepped-on until Contact 4 is reached. When relay PII) is energised the testing of the availability of a free B-line, corresponding with the testing (C-line) described above, takes place over the conductor vb. If a free vb conductor is available, the corresponding relay is operated as for the seizing of the free C-line, the selector Wb is set on the connecting device UeI2 and the connecting path is switched through.

If also no B-line is free the wipers d to 162 are stepped-on until contact 5 is reached. When relay PID is energised the relay PI2 tests over the conductor va. whether a free A-line is available and if this is the case causes the selector Wa to be set on the connecting device Uel2 in a manner corresponding to that described above for the C or B-lines.

If no free A-lines are available the wipers dIl-CZBZ are stepped-on until they reach the contact 6 over which the availability of an S-line is tested. If a free S-line is available the selector Ws is correspondingly set on the connecting device UeIZ over the conductor Us and is set according to the conductor ds marked.

It is understood that over'the wipers dGI and m5l the different groups of lines are tested to see if they are free so that over the corresponding c-conductor (vc, vb, va, vs) a corresponding selector (Wc, Wb, Wa, Ws) is started. Over the Wipers 162 and mI2 to mI'I the d-conductor (dc, db, da, ds) is marked corresponding to the connecting device on which the corresponding selector must test. As soon as Vthis occurs the relays R and RI are energised as shown. The test circuits for the relays PIII and PI2 are broken at the contacts 81H and 88H. Moreover, the transmission of the impulses by the code repeater (KZI may begin. According to the path (C, B, A, S) over which a connection is to be developed the marking number 135 is completely or partly absorbed or completely transmitted.

If for example a C-line is seized the complete marking number 135 is absorbed; only the 4th number which sets the wiper 0140 is transmitted. As described above the relay PII is energised after a C-line is determined; it holds itself energised further over the contact 89p| I. By closing the contact 9IpI I, a contact is immediately marked in the contact bank traversed by the wiper d50 which corresponds to the setting of the wiper dIIIJ sothat the wiper d50 can take up this setting. When this is accomplished the relay P'I is energised over: wiper d50, multipling, wiper 1140, contact Iul, relay Sp, contacts 9IpII, 92pI2, 9302. Further switch operations are described further on.

If, instead of a C-line, a free B-line is seized, relay PI3 is energised after this B-line is selected and a holding circuit is completed over the contact I43pl3. Over the contact IMpI3, contact 5 in the contact bank traversed by the wiper d50 corresponding to the setting of the wiper d3() (3rd dialling of the marking number) is marked so that the wiper d50 takes up this setting and thus, as will be explained later, can transmit 5 impulses. In this case the numbers 1 and 3 are absorbed.

If a free A-line is seized, instead of a B-line the relay PI4 is energised and a holding circuit is completed over the contact I46pl4. Over the contact I4'Ipl4 the wiper 412| is connected so that its sett-ing (on Contact 3) is taken up by the wiper S56. In this case only the number 1 of the marking number is absorbed.

If an S-line is seized, the wiper dI5 set on the contact I is immediately connected since the contacts I5Ic2 and I50pI2 are, as in the above cases, closed. The wiper d50 thereupon takes up the setting of this wiper dI5 and no numbers are absorbed.

The actual stepping-on of the wiper d50 when taking up its position for the purpose of impulse transmission takes place by the well-known a1- ternating reciprocal interaction of the relays I and K when the contact M is closed. The contact I9i transmits the impulses over the conductor 4 and the wiper d2 of the selector AW2 over the connecting device UeI2 while another i-contact operates the magnet, not shown, of the wiper d5 If it is assumed that an S-line is connected with the connecting device Uel2 over the selector Ws the whole marking number 135 is transmitted as described above. The number 1 is marked by the setting of the wiper dI5 on the contact I, the number 3 by the setting of the wiper dZI on the contact 3 and the number 5 by the setting of the wiper on the contact 5. Since now only the relay PI2 is energised and not the relays PI I, PI3 and PI4 only the wiper dI5 is connected; by being set on the contact I in the contact bank traversed by the wiper d50 it marks the contact is disconnected `at contact l51p1.

Yl A'so'that after 'taking one Vstep the wiper vd50 connecte'dipr transmittin'gian impulse, is stopped 4since therelay `P1 is energise'dand the relay I The wiper d50 is thereupon returned toits resting position by an interrupter (not shown). :Relay'iPlli is energised over its"winding II in serieswith the relay P1 so 'that `the wiper dl' Ais disconnected at contact |53pl4 yand over `contact Ilpld the wiper d2l is connected. In the meantime relay P1 restores 'so thatthe next impulsetransmissiontakes place with vthe vwiper d'again being stepped-on from its* rest position. According to the setting of the wiper d2! on contact 3, three impulses are transmitted since therelay `P1 isenergised after wiper (B is set on Contact 3 over: wiper d5!) on confore, overthe contact 192" the wiper d50 is stepped for Athe third time until'the contact 5 marked by the wiper d3 is reached. The relay P1 is now energised in series with the relay PII over: wiper 015D on Contact 5, wiper 1138 on contact 5, contact l45ul, winding II of the relay PII, contacts l44p|3, 90ml, 921212, 93c2. The wiper 013i) is disconnected and the wiper dell is connected. The 4th impulse series is then undertaken by a further operation of the wiper d50 according to the setting of the wiper d40. spending contact is reached the relay P1 is energised in series with the relay Sp. The contacts lsp and llsp give rise to the disconnection of the code repeater KZI. In the connecting device Ue|2 relay P is de-energised, (Fig. 2) and the a-conductor is switched through to the conductor a2 over the contact Nlp; the calling subscriber receives a signal from the exchange and dials the additional numbers required for reaching the required subscriber.

The switch operations described above occur if, before the code repeater KZi is seized, asingle number (l) of the marking number (135) is sent out. If, for example, for setting up a connection within the same toll area (BA1) two numbers have already been selected-cf. Fig. 1, in which for reaching the main network 13 before a connecting device is seized the selectors GW and GW1 are already set-the direction to be used is only developed by the use of a code repeater if the second number marks a different rural main exchange such as is the case, if in the present instance the number 73 is selected. These numbers selected before the code repeater is seized have to be reproduced subsequently. For this purpose a wiper d|3 is provided together with a relay P5. The contact bank traversed by the wiper d|3 is so multipled with the contact bank traversed by the wiper mil that the relay P5 is energised after the wiper has taken the number of steps which correspond to the second number (3) which is to be reproduced. The relay P5 switches in the relays UI, U2 over its contact 21105 whereupon the relay Q2 is energised over the contact 28u2, The wipers m20 to m26 and m to m35, stepped-on after relay P5 is energised, stop when contact 1I is reached since then the relays P8 and P9 are momentarily energised over: wiper m) or m30, contacts 1I, I 59135, I5Bu2, |51u3, l56c2. The relay U3 is energised,

When the corre- I however, so vthat 'theV circuit. described is broken at the'contact I51u3. The wipers m20-m261and mSEl-mSare operateduntil the contact 13 is reached, since this Contact is marked by .thewiper H2 set by the wiper all-3. Theirelays P8 and P9 are again energised. If, later, the numbers to be sent out by the wiper 'd50 are determined the first number ('1) is so formed that lthe relay P1 is again energised after 7 steps by the Vswitch over: wiperA d on contact 1 contacts 25175, tul, winding 1I of the relay PM, contacts l53pl`4,

relayPl is also energised yand completes a holding'circuit for itself over Contact ldpld. When the wiper d50 is operatedasecond time'therelay P1 is then energised in `series with the relay PI3 over: the wiper dei) on contact 3, wiper dl5, contact L3mi, winding II `of vthe relay PI3, vcontacts IAllpl-G, IltplS, MSNM, |5lp|2,-l5lc2. Thus three impulses are transmitted, the two numbers already transmitted by the calling'subscri'ber before the code repeater was seized are reproduced and are transmitted by the'code repeater over an S-line. When using other lines the vappropriate impulse series' are suppressed.

Corresponding operations occur if a Service' call is to be made, for marking which, for example, the numbers 04 are dialled. In this case the relay P6 is operated over the wiper dll! the -relays UI, U2 and Q2 arel energised. The Wipers m20 to m26 and m30 to m36 are first set on the while the next numberis transmitted in manner corresponding to that previously described. When using other lines a part of the impulse transmission is suppressed.

It should be noticed that for transmitting al1 the numbers of the marked number by means of the wiper d50 if two numbers are to be reproduced afterwards, the rst number is transmitted according to the direct marking over the contacts 25105 or 36126 the second number according to the settingr of the wiper dl5, the third according to the setting of wiper`d2! and so on, while for reproducing a number all numbers of the marking number are transmitted by the aid of the wiper d5!) so that the wiper dl5 determines the first number, d2! the second, dl the third and so on.

We claim:

l. In a telephone system, a multi-exchange network, two groups of connecting devices in one of said exchanges, numerical switching apparatus in said one exchange operable to select either of said groups of devices at will and effective thereupon to seize one of` the devices in the selected group, a code repeater common to all of said devices and having a plurality of contacts each corresponding to a diierent one of said devices, means operated upon the seizure of said device by said apparatus to mark the one of said contacts corresponding to the seized device, means in said repeater controlled by the marked contact for determining the one of said devices seized and, at the same time, registering a code depending upon the one of said groups selected, other means in said repeater operated variably to register a code indicative of any other exchange in said network, a direct and an indirect route over which connections may be established between said one exchange and said other exchange, both of said routes accessible to the seized connecting device,v

tension of a connection thereover from the seized connecting device to said other exchange.

2. In a telephone system, a multi-exchange network having alternative routes for setting up connections between exchanges, a repeater in a local one of said exchanges for controlling the extension of connections to the distant exchanges in said network, two groups of connecting devices in said local exchange, means operated to seize a device in one of said groups when it is desired to extend a connection to certain of said distant exchanges and to seize a device in the other of said groups when it is desired to extend a connection to other distant exchanges, means responsive to the seizure of any of said devices for identifying the seized device in said repeater and, at the same time, registering therein the identity of the group to which the seized deviceY belongs, other means in said repeater operated to register the identity of the exchange to which it is desired to extend a connection, said repeater eiective to select a route over which to extend the connection to said desired exchange and at times, in dependence upon the route selected, to repeat al1 or part of said registered information to control switching apparatus to set up the connection over the selected route.

3. A- telephone system as claimed in claim 2, wherein said registration of the identity of the group to which said seized device belongs controls the selection, by said repeater, of the route over which said connection to the desired exchange shall be extended.

4. In a telephone system, wherein connections are set up by automatic equipment under control of the digits of the called stations number, two connecting devices, means for seizing one of said devices at times responsive to the receipt of a certain order of digit of the called stations number and for seizing the other of said devices at times responsive to the receipt of a different order of digit of the called stations number, a controller common to said devices, means for seizing said controller responsive to the seizure of either of said devices and for automatically registering therein the digit which caused that device to be seized, said controller thereafter eiective to control said automatic equipment in accordance with said registered digit to extend a connection from the seized device.

REINHOLD HOEFERT. KONSTANTIN SCHRODER. 

